POS0585 INCIDENCE AND CLINICAL CHARACTERISTICS OF MALIGNANCY IN RHEUMATOID ARTHRITIS PATIENTS – DATA FROM THE MALAYSIAN NATIONAL INFLAMMATORY ARTHRITIS REGISTRY (NIAR)
Authors: S. Selvadurai, H. C. Chong, A. L. Lim, T. Chou Luan, S. A. Wan Mohamad Akbar, V. Y. Tay, C. Y. Lee, H. H. Ariff, D. M. Suahilai, C. R. Ng, N. Kiah Loon, A. H. Ramlan, G. R. Ling, R. Nasadurai, S. Ch’ng Suyin, S. Ahmad Maulana, M. Mohd Zain, S. C. Gun
Journal: Annals of the Rheumatic Diseases (2022)

Background Patients with rheumatoid arthritis (RA) are at increased risk of developing malignancies, particularly hematologic malignancies. This predisposition for malignancy is attributed to the immune dysregulation, chronic inflammation and the long-term use of disease-modifying anti-rheumatic drugs(DMARDs). Objectives This study was undertaken to determine the incidence, patterns of malignancy and identify risk factors of malignancy among RA patients. Methods Individuals diagnosed with cancer after the onset of RA between year 2008 and 2020 from the NIAR RA registry were retrospectively examined. Standardized incidence ratios (SIR) and 95% confidence intervals of various cancers were calculated based on the expected and observed frequencies. The expected number of cases were extracted from the Malaysian National Cancer registry report. ANOVA, Chi-squared, and Student’s t test were used to analyze the risk factors for developing malignancy. Results Of the 3995 patients in the registry, 97 patients developed malignancies at a mean interval of 9.1 years after RA onset. The total follow-up time was 26841.9 person-years. The mean age of patients was 59.3 (± 9.25) years, of which 89.7%(n=87) were women and 40%(n=39) were Chinese. 87.6%(n=84) had solid-organ tumours while 12.4%(n=13) had hematological malignancies. Women showed increased risks of non-Hodgkin’s lymphoma (SIR = 13.1, 95% CI = 9.78 – 17.08), followed by lung cancer (SIR = 12.7, 95% CI = 10.01-15.77) and breast cancer (SIR = 8.8, 95% CI = 7.84 – 9.83). Men showed increased risks of lung cancer (SIR = 3.79, 95% CI = 2.81 – 4.92) and colorectal cancer (SIR = 1.69, 95% CI = 1.09 – 2.42). The risk factors for developing malignancy (p&lt;0.05) include age above 60 years, long duration of RA disease, and higher disease activity states. There were no associations between gender, ethnicity, autoantibodies and DMARDs exposure. Conclusion The overall malignancy incidence was increased among RA patients, with women having a 4-fold higher risk. Though the incidence of solid-organ malignancies is higher, the SIR once adjusted was highest for non-Hodgkin’s lymphoma which is consistent with literature review. Hence, cancer screening with continued vigilance among RA patients is recommended. References [1]Hwajeong Lee. The risk of malignancy in Korean patients with rheumatoid arthritis. Yonsei Med J. 2019;60(2):223-229. [2]X.R. Lim, X. Gao, W.L.J. Tan, L.W. Koh, T.Y. Lian,W.Q. See, K.P. Leong, E.T. Koh •.Abstract: Singapore Patients with Rheumatoid Arthritis Have A Higher Incidence of Solid-Organ Malignancies than The General Population: Findings from The TTSH RA Registry. •bAnnals of the rheumatic diseases, BMJ Journals [3]Summary of Malaysia national cancer registry report 2012-2016, Institut Kanser Negara, Ministry of Health, Malaysia Table 1. SIR of Malignancy among Rheumatoid Arthritis Patients by Sex and Age Groups Sex and Age Group Number of Patients (%) Person-Years Incidence SIR (95% CI * ) Observed Expected Sex (Age Group) Males 10 (10.31%) 48 6 4 1.5 (0.54 - 2.94) Age at Diagnosis 50-60 4 (10.31%) 12 2 2 1 (0.09 - 2.87) 60-70 6 (60%) 36 4 2 2 (0.52 - 4.44) Females 87 (89.69%) 540 59 18 3.28 (2.49 - 4.17) Age at Diagnosis 30-50 12 (13.79%) 31 7 5 1.4 (0.55 - 2.63) 50-60 34 (39.08%) 228 24 10 2.4 (1.54 - 3.46) 60-70 41 (47.13%) 281 28 3 9.33 (6.2 - 13.11) SIR, standardized incidence ratios; CI, confidence interval.Acknowledgements * CI = (√observed number of cancer cases ± 1.96 × 0.5)^2/(expected number of cancer cases). Disclosure of Interests None declared.